Hydraulic torque converters



Oct. 4, 1955 K. G. AHLEN 2,719,616

HYDRAULIC TORQUE CONVERTERS Filed May 27, 1948 9 Sheets-Sheet 2 Oct. 4, 1955 K. G. AHLEN HYDRAULIC TORQUE CONVERTERS 9 Sheets-Sheet 3 Filed May 27, 1948 %M 0 A a v 0 a 5 u w W a z 4 4. W2 My 3 z a z 2 MS .I. \i Tu H V r J .J A 1 4 0 4 1 I F FWWTJHM. M a 3% WWI M M /VENTQA I W z/wza mam 5y Oct. 4, 1955 K. G. AHLEN HYDRAULIC TORQUE CONVERTERS 9 Sheets-Sheet 4 Filed May 27, 1948 9 Sheets-Sheet 5 K. G. AHLEN HYDRAULIC TORQUE CONVERTERS Oct. 4, 1955 Filed May 27, 1948 9 Sheets-Sheet 6 Filed May 27, 1948 Fig.1.

Oct. 4. 1955 K. G. AHLEN HYDRAULIC TORQUE CONVERTERS Filed May 27, 1948 9 Sheets-Sheet 7 V li 1! Fill! vllt 1:414

, v vi. 7 I

III; 'I

Oct. 4, 1955 K. G. AHLEN HYDRAULIC TORQUE CONVERTERS 9 Sheets-Sheet 8 Filed May 27, 1948 NNJ INVE/Y Ti? Oct. 4, 1955 K. ca. AHLEN HYDRAULIC TORQUE CONVERTERS 9 Sheets-Sheet 9 Filed May 27, 1948 INVENTOR KQEL Gusrm/ flux/v ATTORNEY United States Patent O HYDRAULIC TORQUE CONVERTERS Karl Gustav fkhln, Stockholm, Sweden, assiguor, by mesne assignments, to Jarvis C. Marble, New York, N. Y., Leslie M. Merrill, Westfield, N. J., and Percy H. Batten, Racine, Wis., trustees 1 Application May 27, 1948, Serial No. 29,446

4 Claims. (Cl. 192-3.2)

The present invention relates to hydraulic power transmissions or so-called hydraulic torque converters consisting essentially of a pump member, a turbine member and a reaction member, the reaction member generally being arranged as a stationary guide blade ring between the rotating blade rings of the turbine member. The torque converter is employed to multiply the engine torque for starting and for acceleration periods as long as the pump or primary speed n can be kept high enough in relation to the turbine or secondary speed n2. With increasing secondary speed It: relative to the primary speed m, that is increasing speed ratio n2/ m, the secondary torque M2 drops continuously and at the moment when the ratio nz/m is equal to the actual efliciency of the torque converter the primary torque M1 and the secondary torque M2 are equal and there exists no longer any torque multiplication. With further increasing value of nz/ni the secondary torque M2 will be less-than Mi which means that the converter above this mentioned specific point has lost its function as a torque multiplier and has only a negative effect on the power transmission. For this reason the hydraulic torque converters have been provided with some kind of device for establishing direct drive between the input and output shaft as soon as the speed ratio n2/n1 has reached the above-mentioned characteristic value, approximately equaling the value of the converter eificiency. Certain hydraulic converters have been designed to operate as hydraulic couplings at higher speed ratios, and in other systems the type of design is such that the converter will be completely disconnected and direct drive immediately established between the input and output shafts. Both these systems have been used earlier.

The present invention relates primarily to the type of device in which hydraulic drive is combined with means for providing a direct drive to be used in alternation with the hydraulic drive. More particularly the invention contemplates a transmission device in which a primary casing member, a secondary member and a reaction member are rotatably mounted within a stationary housing member.

A general object of the invention is the provision of novel forms of construction whereby the direct drive connection between the primary and secondary members may be established through a connection including a part of the reaction member as a power transmitting element and in which simple and effective means are provided for controlling the operation of the device either as a hydraulic torque converter or as a direct drive power transmitter either manually or automatically under predetermined conditions of operation.

Other and more detailed objects relating to features of control and other more detailed features will appear as the ensuing description proceeds.

For a device according to these general characteristics it is unimportant whather the reaction member is mounted for rotation in one direction or in both directions. If the reaction member is designed for rotation in. both di- 2. rections the resulting advantage will be, that, during its rotation in the opposite direction against the primary and secondary members, a steeper increasing efiiciency curve-that is higher torque multiplicationis obtained if the torque from the reaction member is transmitted via a reverse gearing to the output shaft. When, however, with the above-mentioned design, upon counter-rotation of the reaction member, the top of the efficiency curve has been reached, the efliciency curve will, as known, fall rapidly. F or this reason it is to be preferred to prevent counter-rotation of the reaction member as soon as the single rotating system is more efficient and for this purpose the arrangement according to the invention must be completed with a brake or blocking device, preventing rotation of the reaction member in a direc* tion opposite to that of the primary and secondary members. If this blocking device is made free to engage or disengage, the converter with disengaged blocking device can operate with the reaction member in counter-rotation at the beginning of the starting period and by engaging the locking device change to a system with stationary reaction member. When the suitable speed ratio nz/m for direct drive is reached, the locking device is disengaged again and instead of it the reaction member is connected tothe primary and secondary members of the converter in order to form a connecting and power transmitting member between said members. If a simpler design is desired, the system is provided immediately with a locking device, preventing the rotation of the reaction member in the direction opposite that of the. primary and secondary members. The simplest device for preventing such rotation of the reactionmember is a free wheel, a selflocking brake or an automatic claw-clutch.

In order to connect the reaction member to the primary member a claw-clutch, possibly synchronized, a friction clutchfor instance of friction disc or centrifugal weight type or the likecan be used, whereas the connecting means between reaction member and secondary member canbe carried out more simply and can, for instance, consist of a free wheel or a self-locking brake, preventing the reaction member from rotating faster than the secondary member.

In the following the invention will be .describedmore in detail, referring. to the accompanying drawings, which as examples show some preferred arrangements.

Fig. 1 shows a longitudinal section through a hydraulic torque converter with rotating pump casing and synchronized claw-clutch between the reaction member (guide vane shaft) and primary member (pump casing) as well as a free-wheel clutch between the reaction member and secondary member (turbine shaft) and, finally, a free wheel preventing rotation of the guide vane shaft in a direction opposite to that of the pump and turbine shafts.

Fig. 2 shows an arrangement coresponding to that of Fig. 1 but with a manually operated friction disc clutch instead of synchronized claw-clutch between guide and the pump member.

Fig. 3 shows an arrangement corresponding to that of Fig. 1 but with the synchronized claw-clutch replaced by a centrifugal weight clutch.

Fig. 4 is a section through the centrifugal weight clutch along the lines IVIV in Fig. 3.

Fig. 5 shows an arrangement with pressure fluid actuated friction disc clutch between the guide member shaft and the pump casing.

Figs. 6-9 show details of the control devices to the disc clutch according to Fig. 5, where Figs. 6 and 7 are details showing a valve governed by a centrifugal force actuated weight for regulation of the pressure fluid supply to andfrom the friction clutch, Figs. 8 and 9 are cross-sections through the valve rod showing the channels in the same for the two clutch positions, namely Fig. 8, giving direct passage to the outlet from the working chambers and Fig. 9 showing the inlet passage of pressure fluid to the working chambers of the friction disc clutch.

Fig. 10 is a section along line X-X in Fig. 5.

Fig. 11 shows an arrangement corresponding to Fig. 5, where the reaction member (guide member) is ar ranged for rotating in both directions and provided with a reverse gearing for torque transmission from the reaction member to the output shaft.

Fig. 12 is a section along the line XIIXII in Fig. 11. Fig. 13 is a diagram for an arrangement according to Fig. 11, showing the efficiency, tractive effort and secondary torque curves within the different converter drives as function of the speed ratio n2/ m.

Fig. 14 shows an arrangement of the same type as in Fig. 11 but with a different type of reverse gearing.

Fig. 15 is a section along the line XVXV in Fig. 14.

Fig. 16 shows a corresponding diagram as that of Fig. 13 for an arrangement according to Fig. 14.

Fig. 17 is a longitudinal section of another form of converter embodying the invention.

Fig. 18 is a fragmentary section on enlarged scale of part of the structure shown in Fig. 17.

Fig. 19 is a fragmentary section taken on the line XIX-XIX of Fig. 18; and

Figs. 20 and 21 are sections of the valve member shown in Fig. 18 with the value in different operative positions in the two figures.

In the drawings 10 indicates the crank shaft and 12 the fly-wheel of an internal combustion engine cooperating with the hydraulic converter 14. The housing 16 of the converter (Figs. 2 and 3) is in certain arrangements composed of two parts 16a and 16b, rigidly connected to each other and to the engine casing 18, together with the crank shaft 10 supporting the rotatable parts, bearings and seals of the converter. The primary or pump member 20 of the converter is of the centrifugal type, consisting of the pump discs 24 and 26 and the pump blades 28, supported and driven by the fly-wheel 12 through the hub part 30 and the toothed rims at 32. The secondary or the turbine member consists of two blade rings 34 and 36, the blades of which. are connected as well between the annular discs 38 and 40 as between the disc 40 and the disc 42 extending from the turbine shaft 44. The reaction or guide member consists of a blade ring 46, inserted between the two turbine rings 34 and 36 and supported by the disc extending from the guide member shaft 48. The guide blades are fixed between discs 50 and 52. The blade system of the converter is, consequently, of the two-stage type with rotating outer pump casing according to a design known per se. The torus shaped circuit for the working fluid is outwardly limited by the pump disc 24 and its extension in the shape of a shell 54, both forming the rotating casing, and furthermore by the discs 38 and 42 and the outer part of the disc 50. The inner wall of said circuit is formed by the impeller disc 26 and the discs 40 and 52. The direction of flow of the fluid is indicated by the arrow 56.

The turbine shaft 44 is journaled on the two bearings 58 and 60, which are supported by the pump disc 24 and the stationary casing 16 respectively.

The guide member shaft 48 and its extension 62, as hollow shafts concentrically surrounding the turbine shaft 44, are centered in relation to said shaft 44 by means of the bearings 64 and 66 in the same way that the third bearing 68 supports and centers the guide member shaft against the shell 54, forming part of the rotating pump casing.

In order to prevent unnecessary leakage between the turbine shaft 44 and the guide shaft extension 62 a seal 70 is provided, and for the same reason a seal 72 is provided between the guide shaft 48 and the rotating pump casing.

As the fluid of the hydraulic system preferably operates under a certain basic pressure an auxiliary pump 74as indicated by the drawing-sucks in a suitable quantity of fiuid from the tank 76 and forces it through the cooler 80 in the piping 82 up to a distributing chamber 84 and further through the bores 86 in the guide shaft extension 62, through the space between the turbine and guide shafts, through the bores 78 in the disc 42 to the hydraulic circuit via the narrow space 88 between the discs 24 and 42. The seals 90 and 92, being placed on each side of the distributing chamber 84, thereby prevent unnecessary leakage flow back to the tank 76. The tank in its turn is sealed against the rotating parts of the converter at 94 and 96.

Dangerously high pressure-rises in the hydraulic system are prevented by a spring-loaded valve 98, normally closed, but returning part of the fluid from the circuit to the tank 76 via the bores and 102 in the turbine shaft at excess pressures.

Filling and vent openings are indicated at 104 and 186 respectively as well as a bottom hole 103 for emptying the tank 76. K

In order to obtain direct drive with a torque converter as described above without using a special intermediate shaft between the crank shaft and the driven shaft connected to the turbine shaft, afree-wheel has been inserteda's shown by the dra'wingsbetween the turbine shaft 44 and the guide shaft extension 62, the latter part being rigidly connected to said guide shaft 48 by means of key and groove and a retaining nut 114, pressing the guide shaft extension 62 against a stop ring or step 116 on the shaft 48. This free-wheel 118 is so designed that it prevents the guide or reaction member from rotating faster than the turbine shaft 44 during the conditions when the reaction and the secondary parts have same direction of rotation. A second free-wheel 118 between the guide shaft extension '62 and the stationary casing 161) prevents the reaction member during converter drive from rotating in the opposite direction as compared with the secondary member.

The mechanical connection of the primary or pump member and the reaction or guide member is in the arrangement shown in Fig. 1 effected by means of a synchronized claw-clutch 120 known per se, which consists of the following parts and acts as follows.

A sleeve 1 22 is secured to the hub part of the pump casing part 54 concentrically in relation to the guide shaft 48, the outer circiirn'fe're'rice of the sleeve being provided with a rim of straight teeth or splines 124 and, further, with a conical surface 126, against which surface a second sleeve 128 is supported on a surface of corresponding conical shape. This sleeve 128. is guided in relation to the guide shaft 48 "by splines 130, which are made with comparatively small clearance in'radi'al direction but with large clearance in-periph'eral direction, so that the sleeve 128 will turn from 'one end positio'nto the other in relation to the hollow shaft '48, when the relative speed between pump and guide shaft 48 changes direction. The sleeve 128 also has an outer rim of splines 132 and is pressed against the conical surface 126 by means of springs, acting between the stop ring or step 116 and the end surface of said sleeve 128. A third sleeve 136, sliding'axially on splines along the guide shaft extension 62, has a second inner rim of splines 138, fitting in the rim of splines 124 on the sleeve 122, when the sleeve 136 has been moved to the'left in Fig. 1 by means of, for instance, alever acting upon the two pins 140. It is also characteristic for the design that the rim of splines 132 of the sleeve 128 is locking the sleeve againstaxial movement as long as said first sleeve 128 by the friction forces between the conical surfaces at 126 is peripherally moved to that side, determined by driving the converter so that the pump casing.- has a highenrotational speed than the guide member, but permits an axial movement of said sleeve 136, when the guide member obtains a higher rotational speed than the pump casing and the sleeve is turning over to the peripherally opposite end position.

The shifting from hydraulic to direct drive may preferably occur at the moment when the guide no longer is sub-.

jected to any reaction torque fromthe fluid of the converter circuit and, consequently, the primary or pump member torque and the secondary or output torque of the turbine are equal. This condition occurs at the operation stage when the speed ratio nz/m and the efficiency of the converter are equal. To engage the direct drive clutch in a design according to Fig. 1 it is, however, necessary to give the guide member a speed corresponding to that of the impeller'or even slightly higher. As the freewheel 110 at the same time is so designed as to prevent the guide member shaft from running faster than the turbine shaft, the adjustment to the correct relation between the impeller and guide member speeds may only be effected by decreasing the torque of the engine. A momentary throttling of the fuel supply to the engine and by this decreasing the speed of the primary member can temporarily make the guide member shaft overrun the pump casing speed, whereby the sleeve 126 turns and unlocks the sleeve 136, so that direct drive can be established by moving over said sleeve 136 to the left, thereby engaging the rims 124 and 138. Consequently, direct drive is achieved, owing to the fact that, as mentioned above, the free-wheel 110 prevents the tubine from running slower than the guide member.

The return from direct drive to converter drive is achieved by moving the sleeve back into the position shown in Fig. 1.

Fig. 2 shows a slightly modified design of the arrangement according to Fig. 1. V

The difference between the two designs is chiefly that the synchronized clutch 120 is exchanged for a friction clutch 150 of conventional type. This friction clutch consists of a disc 152, rigidly connected to the pump casing, against which a second friction disc 154 can be pressed by means of a disc 156, supported bybut axially movable on-a ring 158, rigidly connected to the pump casing 54. The friction disc 154 in its turn is carried by a hub 169, which by means of key and groove or splines 162 is axially movable on the extension 62 of the guide member shaft. In order to have the possibility of engaging and disengaging the friction clutch asp ring disc 168 is mounted between a projection of part 158 of the rotating pump casing, a ridge on the disc 156 and an outer ring on the axially movable ball bearing 166. The inner ring of the bearing 166 is secured to a sleeve 164, provided with connection means for a forked lever (not shown by the figure) and slidably, but not turnably, journaled on a hub 170, fixed to the casing 16 and concentric in relation to the turbine shaft. Direct drive can for this arrangement be established independently of the torque on the reaction member and without previously decreasing the motor speed, in contrast to the design according to Fig. 1. The

return to converter drive is effected in the same Way as mentioned for the previous design by disengaging the friction clutch.

Figs. 3 and 4 illustrate a design where the connection between the pump casing and the guide member is established by means of a so-called centrifugal weight clutch, which is engaged as soon as the reaction member begins to rotate. The change from converter drive to direct drive and vice versa for this arrangement is established automatically at a suitable point of operation of the hydraulic system.

Owing to the fact that other parts of the converter have not been essentially altered compared to the description in connection with Figs. 1 and 2, the following detailed description of this arrangement according to Figs. 3 and 4 is limited to the clutch'itself between the pump casing and guide member shaft as well as the operation of said clutch when engaged and disengaged.

The extension 62 of the guide member-shaft is formed at one end as a flange 202, supportinga ring 204' with. U-shaped outer rim where a number of brake shoes 206" and onlyinsure that the shoes are out of touch with the brake band 212, fixed to a ring member 214 projecting from the pump casing, when the guide member is stationary.

Any leakage fluid from the seals is caughtby the groove 216 at the inside ofring 204 and conducted through bores 218 toward the rim edge 220, formed in a suitable manner according to the figure, so that the leakage fluid flows down or is thrown outwardly against the groove 222, where the fluid is collected and drained through the bore 224 into the lower part of the groove. This arrangement is used in order to keep the braking surfaces dry and, consequently, guarantee a maximum of braking effect. I

The clutch operates in the following-manner: at low speed ratios nz/m between the primary andsec'ondary members the guide member is actuated by a torque from; the fluid in the circuit, tending to turn said guide member" in a direction opposite to that of the primary'mernber, a1 rotation, however, that is prevented by 'the free-wheel 118, locking the guide member to the casing 16 as long.

as the torque has the mentioned direction. With increasing speed ratio nz/m the reaction torque decreases. progressively first to zero and 'then changes direction of action, so thatthe guide member, no longer locked against rotation by the free-wheel118, starts rotatingin the same directionas the impeller and turbine. The

centrifugal force that acts on the brake shoes when the guide member rotates exceeds the spring-force of. the pins 208, and as soon as the shoes 206 come in contact with the brake band 212 the rotation of the guide member is further accelerated by the directly transmitted primary torque. This action rapidly increases the surface presisurebetween the shoes and the brake band and, consequently, rapidly increases the friction torque of the clutch so that the guide member is locked to the pump casing. At the same'time the -free-wheel -causes the turbine and pump or primary member to rotate at the same speed.

The return from direct to converter drive with this clutch arrangement occurs as soonas the torque speed ratio Mr/m of the engine exceeds a certain limit value;

where the engine torque is higher than the maximum torque transferable via the centrifugal weight clutch at the actual speed m. In such case the clutch begins to slip, further diminishing the friction torque bydecreasing surface pressure between the'shoes and the friction band 212, as well as by decreased specific friction coeflicient when changing from stationary to'sliding friction, at the same time that the fluid in the circuit begins to circulate, acting on the guide member with a torque having a direction opposite to that of the rotation of the impeller.

In the arrangement according to this invention illustrated'by Fig. 5 and associated Figs. 6-10 the connecting member between the primary and the reaction member consists of a fluid-actuated friction clutch 250, but other parts of the converter are substantially identical to previously described arrangements, especially with regard to the position of the free-wheelsbetween the turbine and the guide member shafts as well as between the guide member shaft and the casing. The inlet and outlet openings'for the operating fluid to and from the clutch are automatically controlled by a valve system, receiving its operating impulses from the guide member. In any case,

however, this shifting can also be done manually by means of a separate control system.

The extension 62 of the guide member shaft has in Fig. a bell-shaped member 252 carrying in its turn three friction discs 254, a stationary side wall 256 and a second axially movable side wall (or plunger) 258', thelatter wall being provided with sealing members 260 and 262 respectively at the inner and outer circumference against the bell 252, which in this way creates an operating chamber 264 for the pressure fluid delivered by the gear pump 74. By means of a radial bore 266 in said bell 252 the operating chamber 264 can be made to communicate with or be cut off from the channel system for pressure fluid from the pump 74 by shifting a valve 268, mounted inthe outer part of said bore 266. In cutting off the operating chamber 264 from communicating with the pressure fluid the valve 268 simultaneously opens an outlet 284 for emptying said operating chamber. The primary member of the friction clutch consists of three discs 270, supported by a hub 272 that is fixed to the impeller casing.

The design of valve 268 on a large scale is shown by Figs. 6-9. The valve sleeve 274 is rotatably mounted in an axial bore in the bell 252 as well as in a bore through a supporting bracket 276 fixed to said bell.

From the sleeve there also extends a lever with weight 278 and projection 280; the latter rests when the clutch is disengagedagainst a suitable surface of the bracket 276 owing to the spring force of the valve spring 282. This valve position-indicated by a in Fig. 6-makes, as shown by Figs. 7 and 8, the outlet 286 communicate with the operating chamber 264 by the sleeve channel 284 when at the same time communication with thebore 266 is interrupted. Consequently, the operating chamber will be emptied in this position, that is the the clutch will be disengaged and the reaction member disconnected from the impeller casing, which means that the torque transmission is effected via the hydraulic converter system.

As soon as the operating conditions of the converter are changed so that the reaction torque on the guide member rotates said member in the same direction as the impeller, the centrifugal weight 278 is turned over to position b by the centrifugal force and the valve position will be that illustrated by Fig. 9. The outlet 286 is now closed and pressure fluid enters the operating chamber from the bore 266 via the groove 288 in the valve sleeve 274 and presses the two clutch halves against each other, rigidly connecting the pump and reaction members, whereupon the free-wheel 110 between the turbine and reaction member will accomplish the direct drive. The pressure fluid to the operating chamber must not necessarily be supplied under especially high pressure, due to the fact that the influence of the centrifugal force will in any case provide sufficiently high fluid pressur on the piston 258.

The change from direct drive to converter drive is achieved automatically in a similar manner as described for the centrifugal weight clutch according to Figs. 3 and 4. With increasing value M1/ 111 the engine torque exceeds the friction torque of the clutch at a certain speed n1 so that the two clutch halves begin to slip. Owing to this the fluid pressure in the operating chamber ofthe clutch decreases rapidly when at the same time the fluid in the converter circuit starts circulating, thereby providing a reaction torque on the guide member and slowingdown same into stationary position against the free-wheel 118, whereupon spring 282 can bring the sleeve from position, b back to position a, in order that the operating chamber 264 of the clutch may be emptied.

Fig. 5 shows also an arrangement by the aid of which the shifting to and from direct drive can be achieved manually. The ring 290, fixed to the casing, is provided on the outer race with threads, engaging an outer ring 292 slidingin cooperating threads when turned by the lever 294, which with one end acts in a groove on the circumference of the ring 292 and with its other end is connected to the shaft 296, rotatably mounted in the casing and in its turn controlled by the aid of the lever 298. Obviously, when turning the lever 294 in one direction or the other the outer ring 292 will be moved to the right or the left. If moved to the right the beveled surface 300 of said ring will raise the weight 278 from position a to position b, which, as has been described earlier, results in a supply of pressurefluid to the clutch 250 and shifting from converter to direct. drive. If the ring ismoved to the left, the annular projection 302' of said ring will brake against the valve sleeve part 304, creating a turning movementof said valve sleeve and returning it to position a, so that the drive will be done via the hydraulic converter system.

In order to help the lever 294 and the ring 292 into new tral position between the operating positions described above, the ring 292 is provided with two projections 306 as retainers for the springs 308, 310, 312 and 314, extending between the casing and the retainers as well as between the retainers and the lever 294.

Figs. 11 and 12 show a modified design of the converter as illustrated by Fig. 5, a design permitting the turbine side to rotate as a double or counter-rotation system as well as single rotation system. The shifting from one type of operation to the other is done by means of servomotors, and to transmit torque from the reaction member operating as a double rotation stage to the turbine shaft 2 reverse gear has been adopted.

The friction clutch between the pump and the reaction member is of the same design as described in connection with Fig. 5, but the fluid pressure regulating sleeve is in this case controlled by a servomotor 352, the piston of which acts on a forked lever 354 that in its turn axially moves the ring 356 and the sleeve 350 fixed to said ring.

The free-wheel 118 according to Figs. l-S is substituted by a brake 358 between the reaction member and the stationary casing (as shown in Fig. ll), said brake consisting of a brake band 360 and a lever system 364 actuated by the servomotor 362. The brake drum is formed on the bell 252, surrounding the friction clutch. The brake has to lock during those operating conditions when the guide vanes must operate as stationary reaction member but is free during double rotation and direct drive.

The reverse gear between the extension 62 of the guide member shaft and the turbine shaft 44 consists of a gear 366 formed as one single piece with the extension 62, a gear 368 secured to the turbine shaft and planet gears 370, supported by pins projecting from a ring 376 rotatably supported by the bearings 372 and 374. A free-wheel 378 between said ring and the casing prevents the ring from rorating in a direction opposite that of the pump but leaves it free to rotate in the same direction. In other words, the

. reverse gear is inactive under all conditions except when torque applied in counter-rotation direction from the blading 46 is transmitted throughthe gear.

The pressure fluid to the friction clutch and to the two servomotors is provided by a gear pump 380, driven by the primary member of the converter via the three gears.

382, 384 and 386. The pump sucks in fluid through the opening 388 and delivers it to the bore 390, branching into two bores 392 and 394, the first of which communicates with the channel system of the regulation sleeve 396 and the, second of which is connected to the converter circuit in substantially the same way as has been described for the pump 74 in Fig. 1.

-At a valve position as indicated bya in Fig. 11 the communication between the servomotors and the pressure pipe 392 is interrupted and, instead, said motors are in open communication with the bottom tank of the converter via the channels 398 and 402, 400 and 404 respectively, so that the spring-loaded servomotor pistons can take the positions that correspond to emptied cylinders.

The servomotor 352 and the sleeve 350 are thereby mechanically so connected via the ring 356 and the lever 354 that said sleeve establishes open communication between the operating chamber 264 and the outlet opening 286 at the same moment when the pressure pipe is closed, a position corresponding to disengaged friction clutch. The servomotor 366 whose piston rod acts on the lever system 364 connected to the brake band 360 also releases the guide member in this position, so that said guide member is mechanically connected to the turbine shaft only by the reverse gearing but, for the rest, can rotate freely under the influence of the fluid flow in the converter circuit. At low speed ratios n2/n1, for instance at starting, the arrangement as to Fig. 11 is especially advantageous due.

to the fact that the reaction member rotates in a direction opposite to that of the blade rings 34 and 36 so that the high torque multiplication of the double rotation turbine can be utilized.

Fig. 13 is a diagram showing the relation between the efiiciency 1 and the output torque Mz as function of the speed ratios nz/ m in a converter according to Figs. 11 and 12. The efliciency curve consists of three branches a, b and corresponding to the efiiciency curves for double rotation, single rotation and direct drive respectively.

In Fig. 12 the arrow A indicates the direction of rotation of the turbine shaft and the arrow B the corresponding direction of the guide member during double rotation drive. As appears from Fig. 12 the design of the free-wheel 110 permits such drive. The torque acting upon the reaction member is carried over to the turbine shaft by means of the before-mentioned reverse gears 366, 368 and 370. The ring 376 is subjected to torque trying to turn the ring in a direction opposite to that of the impeller but this movement is prevented by the free-wheel 378. Due to smaller diameter of the gear 366 cionnected to the counter-rotatng blading 46 as compared with the ring gear 368 connected to the driven shaft, the speed of rotation of the counter-rotating blading is higher than that of the forwardly rotating turbine blading 34, 36.

If the regulation sleeve is moved to position b in Fig. 11 the conditions for the servomotor 352 will be unchanged but the outlet of the other servomotor 362 is closed and the working chamber is connected to the pressure pipe 392, whereupon the inducted fluid moves the servomotor piston to its other end position, immediately resulting in a locking of the guide member to the casing by means of the brake 358. After that, the secondary member of the converter operates as a single rotation turbine having an efiiciency curve the peak of which is moved to higher n2/n1 values as compared with the characteristics of the double rotation system.

During this operation at point b (single rotation) the ring 376 with the planet gears 370 rotates between the gears 366 and 368 in the same direction as the turbine shaft without transmitting any torque, released by the free-wheel 378. 1

By moving the regulation sleeve 396 over to positionc the two servomotors reverse their action compared with position b. The servomotor 362 is cut off from the pressure pipe 392 and the outlet for the operating fluid opens again to the bottom tank, resulting in a release of the brake band 360 acting on the reaction memben Simultaneously, the outlet from the operating chamber of the servomotor 352 is closed and communication opened to the pressure pipe 392, resulting in a move-:

ment of the ring 356 that carries the sleeves 350, so that, after closing the outlet 286, the operating chamber 264 of the friction clutch is made to communicate with the radial bore 266 with the result that pressure fluid starts acting upon the piston 258 and engages the clutch compelling the reaction member and, by means of the freewheel 110, also the turbine member, to have the same speed as the pump. Direct drive is thus established.

-The reverse gearing 376 now rotates in thesame' di rection and with the-same speed of-rotation' as there? maining rotating parts of the converter.

of the brake members. a

Figs. 14-15 show a modification of the reverse gearing as illustrated in Figs. 11-13.

The planet gears 500 are mounted on shafts 502, directly connected to the converter casing. These planet gears mesh with a toothed rim on the bell 252 as well as a gear 512 journaled at 508 and 510 on the sleeve 506.

In the same manner as for the previously described arrangement the position it corresponds to a condition of operation where the reaction member rotates in a direction opposite to that of the pump, that is double rotattion drive, at low speed ratios nz/m. A free-wheel 514 during this operation prevents the sun gear 512 from rotating relative to the sleeve 506 and the turbine shaft 44.

In this instance, in contrast with the case of the construction shown in Fig. 11, the blading 46, connected to the ring gear 504, rotates at lower speed than does the forwardly rotating turbine blading 34, 36 which is connected to the smaller sun gear 512. The reversing gearing can in this case as well as in the design according to Figs. 11-13 be composed of conical gears in order to facilitate a changed gear ratio, if desired.

In position b of the sleeve 596the band brake locks the reaction member to the casing. The sleeve 506, released by the free-Wheel 514, now can-rotate freely in relation to the stationary gear 512.

In position 0 of the sleeve 5%. the hand brake releases the reaction member at the same moment when the friction clutch is engaged and connects the pump and reaction members. The free-wheel between the reaction and turbine members also forces the latter to take primary speed when at the same time the free-wheel 514 is free-wheeling.

With the double rotation type of converter, of which the embodiments shown in Figs. 11 and 13 are examples, higher torque multiplication at stall is obtained than with a single rotation converter, other things being equal.- The reason for this may be explained as follows. In all cases the secondary or output torque must equal the sum of the primary or input torque and the reaction torque transmitted to the stationary casing or other stationary abutment. This may be expressed for the cases of the two different types of converters by means of the following equations:

Single rotation M2=M1+R1(R1=R). Double rotation M2=M1+R1(Ri=R+R a) in which:

reaction member driven member In the case of the single rotation converter all of the hydraulically applied reaction torque R is transmitted to the stationary, casing and therefore R1 equals R. In the case of the double rotation converter, however, in which the reaction and driven members are geared together, the reaction torque transmitted to the casing through whichever member of the gearing may be anchored is not equal to the reaction torque applied to the blading but is equal to the value of that torque plus the value of that torque multiplied by the ratio of the gearing between the reactionmember and the driven member. Thus, in all cases, the value of M2 at stall, other things being equal, will be greater in the case of the double rotation converter than in the case of the a is gear ratio of earners;

11 single rotation. converter, by the amountof the factor X If we now consider the embodiment oh the double rotation converter shown in: Fig. 11 itwill be apparent from the drawing that the diameter of the sun gear 366 to which the reaction member is connected isapproximately half the diameter of the ring gear 368 connected to the driven member. Consequently, the value of the gear ratio a. is approximately 2 and represents torque multiplication of; the hydraulic torque imposed on the bladesi46, which ashas previously been noted, rotate at a. higher speed than do the turbine blades 34 and 36 with this gear arrangement;

On: the other hand; inthe case of the arrangement shown in Fig. 1'4- the reverse is true, the diameter of the ring gear 504 to which the reaction blades areconnected being approximately double the diameter of'the sun gear 512" which is connected through the free-wheel 110 to the turbine member. In thiscase the gear ratio a is 0.5, so that the value of the torque applied to the drivenmember from the reaction blading is less in this case than in the construction shown in. Fig. 11. However, even in this case the value of the total torque on the secondary member is greater than would: be the case with a single rotation converter. e

The reason for utilizing different gear arrangements resulting in different stall torque characteristics in converters which are otherwise substantially the same is best illustrated by comparison of Figs. 18 and 16- showing' secondary torque and efficiency characteristics in terms of the speed ratio nz/m between the primary and secondary members. As shown in both of these figures the curve arepresents the efficiency of the converter in double rotation operation, curve b the converter eificiency in single rotation operation and cthe efficiency in direct drive; As previously'noted the secondary torque M2 at stall obtainable with the design'of-Fig. 11 is higher than the comparable torque obtainable with the design of Fig. 14, but owing to the higher rate of'spced of rotationof the reaction bladingin double rotation opera tion, which is characteristic of the design of Fig. 11, the efiiciency of the converter not only rises very rapidly with increase of nz/m from stall but also falls comparatively rapidly at a relatively low value of nz/m. On the other hand, with the arrangement shown in Fig. 14, while the secondary torque at stall is lower, the lower sp'eedof' rotation of the reaction blades in double rotation operation results in the production. of an efficiency curve which while notrising so rapidly from stall as the curve a of Fig. 13, maintains relatively high efficiency until a higher value of n2/ n1 is obtained. Consequently,. double rotation operation. may be. efficiently maintainedv to higher vehicle speed with the arrangement shown in Fig. 14 than with the arrangement shown in Fig. 11, and while the maximum torque obtainable at stall with the former arrangement is lower than with the latter, the advantage of the relatively higher torque multiplication obtainable with double rotation operationmay be used over a wider vehicle speed with the former than with the latter.

The value to be chosen of the gear ratio between the reaction and turbine members in a double rotation converter will be dictated largely by the operating characteristics desired fora given vehicle, and also the power and torque characteristics of the engine-which furnishes the motive power. In this connection, however; it is to be noted that with a proper gear ratio between the reaction member and the turbine member of a doublerotation converter a. sufiiciently high stall torque multiplication characteristic may readily be obtained in the converter. to equal or exceed the adhesion capacity of the the vehiclewheels: when the motive power for. the con: verter is supplied; by an engine of the size and powersuitable. for. giving desired operating characteristics. to the vehiclethroughoutitsi normal speed; range.

Gil

In all: of the preceding embodiments hereinabove described, direct drive is, obtained by connecting the ro-' tating casing to. the reaction member by means ofv a clutch which may. be of any desired specific type and run the reaction member, even if the latter is clutched tothe rotating casing, at anytime when the former tendstorotate faster than; the latter. With the previously illustrated embodiments hydraulic braking is possible since if the driven shaft speed exceeds the pump speed, which is determined by the speed ofoperation of the engine, the turbine blades turning at a faster rate than the pump blades will create what is in efiect a form of coupling connection between the driven shaft and the engine. In the previously described embodiments direct mechanical braking by the engine can be effected by introducing, in known manner, an overrunning clutch between the driven and driving shafts, so arranged as to engage when the driven shaft tends to rotate at a higher speed than the driving shaft. This expedient, however, involves the use of an additional clutch with consequent added cost. In some installations the use of engine braking may be a highly desirable and necessary characteristic, and in Figs. l-'7-21- there is illustrated a further form of converter embodying the invention which will permit direct mechanical braking with the engine without increasing the.

number of clutches required for the operation of the transmission; This embodiment is essentially of the same general construction as that shown in Fig. 5 and associatedfigures, corresponding parts being correspondingly indicated, and therefore need not be described in detail-except insofar as the difference in the clutch arrangement is concerned; In the present embodiment the construction of the clutch 250 for connecting the rotating casing-54 with the bell portion 252 of the reaction member is the same as previously described, the admission and release of fluidfor actuating the axially movable clutch plunger 258 being controlled by the valve 268 which is actuated by means of the centrifugal weights 278- to control the fluid passages in the manner pre-' viously described in connection with Fig. 5. In the present construction, however, a second multiple disc clutch 250a-is provided having axially movable friction discs 254w arranged to turn with the bell portion and axially movable discs 278a mounted to turn with the driven member 44.

The'axiallyfixed backing plate 256a of the bell portion 252 provides the inner race 62 of the overrunning clutch 118-, the outer race of which is provided by the ring 290 fixed to the stationary casing and threadedly engaging the outer ring 292 adapted to be turned manually through the medium of the element 294 so as to actuate valve 268 due to-thethreaded engagement between parts 290 and 292 and the element 268;: fixed to the valve member and engaging-a suitableprojecting rim 29201 on the ring 292.

Theaction of the valve in admitting actuatiing fluidto and reieasingit from the clutch 250 is the same as previously' described in connection with Fig. 5, and when fluid is admitted to the pressure chamber of clutch 250; it is-also admitted to the clutch 250a through the cross channel 286a in-the bell portion 252 so that both clutches are engaged or released simultaneously, or, if desired, d'ue=to-the fact that the channel 286:: may be made relatively small so that it will act asa throttling orifice, the

action may. be made such that the clutch 250 engages slightly aheadof clutch 250a..

From the preceding description of Fig. 5, the operatiomofithe apparatuszinshifting from hydraulic to direct dri-Yeaandwice ve'rsa. willreadily be understood, and it.- will further be seen that owing to the fact that the rotating casing is connected to the reaction member through the medium of a friction clutch and the latter member is connected to the drive member through another friction clutch, a mechanical" connection is provided between the rotating casing and the driven member when the clutches are engaged which will permit transmission of torque between the casing and the driven member regardless of whether the casing tends to rotate faster than the driven shaft or vice versa.

From the foregoing it will be evident that the principles of the invention may be embodied in many different specific forms of construction and are applicable both to single rotation and double rotation converters and that certain novel features of the invention may be used to the exclusion of others. Accordingly the scope of the invention is to be understood as embodying all forms of apparatus falling within the scope of the appended claims and is not to be limited to the specific construction herein disclosed by way of example.

What I claim is:

1. A hydraulic torque converter having a rotating casing constituting a primary member providing pump blading, a secondary member providing turbine blading and a reaction member providing reaction blading, clutch means for mechanically connecting said reaction member at the same time in power-transmitting relation to both the primary member and the secondary member to provide a mechanical drive in which torque is transmitted from the primary member to the secondary member through the reaction member, said clutch means comprising a rotatably mounted clutch member rotationally fixed with respect to said reaction member, first fluid pressure actuated means providing a first friction clutch for connecting said clutch member and said primary member, second fluid pressure actuated means providing a second friction clutch for connecting said clutch member and said secondary member, means for admitting pressure fluid to said clutch member, valve means carried by said clutch member and movable to control said pressure fluid to selectively cause engagement and disengagement of said clutches and means comprising centrifugal weights mounted to rotate with said clutch member for actuating said valve means to effect engagement of said clutches upon rotation of said clutch member in the same direction of rotation as that of said primary member.

2. An apparatus as defined in claim 1 including means for selectively actuating said valve means independently of said centrifugal weights to effect engagement of said clutches.

3. An apparatus as defined in claim 1 including means operable upon actuation of said valve means for admitting pressure fluid to said first and said second fluid-actuated means to cause engagement of said first clutch ahead of the engagement of said second clutch.

4. An apparatus as defined in claim 1 including a pump for supplying pressure fluid to the working chamber of said torque converter and the means for admitting pressure fluid to said clutch member comprising a passage in communication with the delivery side of said pump.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Aug. 2, 1935 

